Semiconductor device and method of fabricating the semiconductor device

Abstract

A semiconductor device may include a first semiconductor layer formed on a substrate, a second semiconductor layer formed on the first semiconductor layer, a source electrode and a drain electrode in contact with the first semiconductor layer or the second semiconductor layer, an opening formed in the second semiconductor layer, an insulating film formed on an inner surface of the opening formed in the second semiconductor layer and above the second semiconductor layer, a gate electrode formed in the opening via the insulating film, and a protective film formed on the insulating film and including an amorphous film containing carbon as a major component.

What is claimed is: 
     
       1. A semiconductor device comprising:
 a first semiconductor layer formed on a substrate; 
 a second semiconductor layer formed on the first semiconductor layer; 
 a source electrode and a drain electrode in contact with the first semiconductor layer or the second semiconductor layer; 
 an opening formed in the second semiconductor layer; 
 an insulating film formed on an inner surface of the opening formed in the second semiconductor layer and above the second semiconductor layer; 
 a gate electrode formed in the opening via the insulating film; and 
 a protective film formed on the insulating film and including an amorphous film containing carbon as a major component. 
 
     
     
       2. The semiconductor device as claimed in  claim 1 ,
 wherein the protective film includes the amorphous film and an insulating protective film, 
 wherein the amorphous film is formed on the insulating film, and 
 wherein the insulating protective film is formed on the amorphous film. 
 
     
     
       3. The semiconductor device as claimed in  claim 1 ,
 wherein the protective film includes the amorphous film, a first insulating protective film, and a second insulating protective film, 
 wherein the first insulating protective film is formed on the insulating film, 
 wherein the amorphous film is formed on the first insulating protective film, and 
 wherein the second insulating protective film is formed on the amorphous film. 
 
     
     
       4. The semiconductor device as claimed in  claim 1 , wherein a thickness range of the amorphous film is 1 nm or more and 30 nm or less. 
     
     
       5. The semiconductor device as claimed in  claim 1 , wherein a ratio of carbon-carbon bonding in the amorphous film is represented by sp2≦sp3. 
     
     
       6. The semiconductor device as claimed in  claim 1 , wherein a density range of the amorphous film is 2.7 g/cm 3  or higher and 3.56 g/cm 3  or less. 
     
     
       7. The semiconductor device as claimed in  claim 1 , wherein the insulating film is made of aluminum oxide. 
     
     
       8. The semiconductor device as claimed in  claim 1 , wherein the first semiconductor layer includes gallium nitride (GaN). 
     
     
       9. The semiconductor device as claimed in  claim 1 , wherein the second semiconductor layer includes aluminum gallium nitride (AlGaN). 
     
     
       10. The semiconductor device as claimed in  claim 1 , further comprising:
 a third semiconductor layer disposed between the second semiconductor layer and the insulating film, wherein the third semiconductor layer includes n-type gallium nitride (n-GaN). 
 
     
     
       11. The semiconductor device as claimed in  claim 1 , the semiconductor device being configured to function as a high electron mobility transistor (HEMT). 
     
     
       12. The semiconductor device as claimed in  claim 2 , wherein the insulating protective film includes silicon nitride. 
     
     
       13. The semiconductor device as claimed in  claim 3 , wherein the second insulating protective film includes silicon nitride. 
     
     
       14. The semiconductor device as claimed in  claim 3 , wherein the first insulating protective film is made of a material the same as that of the insulating film. 
     
     
       15. A semiconductor device comprising:
 a first semiconductor layer formed on a substrate; 
 a second semiconductor layer formed on the first semiconductor layer; 
 a source electrode and a drain electrode in contact with the first semiconductor layer or the second semiconductor layer; 
 an insulating film formed above the second semiconductor layer; 
 a gate electrode formed on the insulator; and 
 a protective film formed on the insulating film and including an amorphous film containing carbon as a major component. 
 
     
     
       16. A method of fabricating a semiconductor device, comprising:
 forming a first semiconductor layer on a substrate and a second semiconductor layer on the first semiconductor layer; 
 forming a source electrode and a drain electrode in contact with the first semiconductor layer or the second semiconductor layer; 
 forming an opening in the second semiconductor layer; 
 forming an insulating film on an inner surface of the opening formed in the second semiconductor layer and above the second semiconductor layer; 
 forming a gate electrode in the opening via the insulating film; and 
 forming a protective film including an amorphous film containing carbon as a major component on an exposed part of the insulating film. 
 
     
     
       17. The method as claimed in  claim 16 ,
 wherein the forming the protective film includes 
 forming the amorphous film on the insulating film, and 
 forming an insulating protective film on the amorphous film. 
 
     
     
       18. The method as claimed in  claim 16 ,
 wherein the forming the protective film includes 
 forming a first insulating protective film on the insulating film, 
 forming the amorphous film on the first insulating protective film, and 
 forming a second insulating protective film on the amorphous film. 
 
     
     
       19. The method as claimed in  claim 16 ,
 wherein the amorphous film is formed by filtered cathodic arc deposition. 
 
     
     
       20. A method of fabricating a semiconductor device, comprising:
 forming a first semiconductor layer on a substrate and a second semiconductor layer on the first semiconductor layer; 
 forming a source electrode and a drain electrode in contact with the first semiconductor layer or the second semiconductor layer; 
 forming an insulating film above the second semiconductor layer; 
 forming a gate electrode on a part of the insulating film; and 
 forming a protective film including an amorphous film containing carbon as a major component on an exposed part of the insulating film.